Regulatory effects of dietary n-3 and n-6 lipids on plasma and hepatic lipid levels, liver cell number and microsomal protein content in spontaneously hypertensive rats.

Weanling male spontaneously hypertensive rats were fed semipurified diets containing either corn or fish oil for 8 weeks. Rats fed on fish oil diet had significantly lower plasma triglyceride, total cholesterol and HDL-cholesterol levels than rats fed on corn oil diet (P < 0.05). Moreover, rats fed on fish oil diet had significantly lower liver total lipid and triglyceride concentrations than rats fed on corn oil diet (P < 0.05). Dietary lipids were reflected in plasma fatty acid composition. Rats fed on fish oil diet had significantly greater plasma eicosapentaenoate (EPA) and docosahexaenoate (DHA) (n-3 PUFAs) with an accompanying decrease in plasma linoleate (LA) and arachidonate (AA) (n-6 PUFAs), in comparison with the rats fed corn oil (P < 0.05). Those results would suggest that the n-3 PUFAs were incorporated into plasma lipids at the expense of the n-6 PUFAs. Rats fed on corn oil diet had significantly greater liver DNA content than rats fed on fish oil diet (P < 0.05), thereby implying that the n-3 PUFAs in fish oil had an inhibitory effect on liver cell proliferation. Furthermore, rats fed on fish oil diet had significantly greater hepatic microsomal protein content than rats fed on corn oil diet (P < 0.05), indicating that fish oil exerted a stimulatory effect on hepatic microsomal enzymes.